Patent Document 1 describes an image display device that displays an image by scanning the projection surface by a light beam that is modulated according to a video signal. This image display device includes condensing optics that condense the light beam from a light source and a scanning unit provided with a reflecting mirror that reflects the light beam that has been condensed by these condensing optics toward the projection surface.
The condensing optics form a beam waist at a position farther from the reflecting mirror than the midpoint between the reflecting mirror and the projection surface. In this way, the beam diameter on the reflecting mirror of the scanning unit can be reduced, and moreover, enlargement of the beam diameter on the projection surface can be suppressed, thereby enabling a more compact reflecting mirror and higher-definition image display.